The present invention relates to a screen printer, and more particularly, to a screen printer equipped with a mask cleaning device which serves to remove ink dregs adhered to one surface of a mask and holes formed in the mask. Although not limitative, the screen printer of this kind is suitable to form a film on an electronic circuit board or substrate.
Repetition of the film formation on the substrate due to the screen printing process causes ink to remain on a mask surface adjacent to the substrate and in holes of the mask. If the printing is further continued, the remaining ink will bring about defective printing such as blot, blur, discontinuity of line or the like of an ink pattern printed on the substrate. For this reason, it is necessary to wipe the adhered ink dregs by cleaning the mask each time the printing has been repeated a predetermined number of times.
On the other hand, with the development of electronics, a mask is required to obtain high definition. That is, the area of hole pattern on the mask and the space between adjacent holes tend to be reduced. As a result, the ink remains in the holes of the mask as well as adhere to the lower surface of the mask. To cope with this, it is necessary to increase the frequency of mask cleaning.
Heretofore, cleaning of the mask has been performed by hand. However, the operation by hand alone cannot cope with the increase of the frequency of mask cleaning so that not only the printing efficiency is deteriorated but also defective printing is increased.
Recently, devices for automatically performing the cleaning have been proposed. These automatic cleaning devices are disclosed in Japanese Patent Unexamined Publication Nos. 62-152853, 63-173643 and 63-296942 as well as in Japanese Utility Model Unexamined Publication Nos. 60-85931 and 62-178145, for example.
However, the proposed devices including the cleaning by hand are not satisfactory in terms of the cleaning efficiency and the ability to remove the ink dregs.